When we are called out to a roof that started leaking a few years after it was replaced, the shingle is rarely the problem. Here are the seven causes we see in Oklahoma City, and what a correct job does instead.
1. Roofing over the existing layer instead of tearing off
Installing a new roof over an old one is faster and cheaper, and it is the single most consequential shortcut in the trade. The reason is not the extra weight, although that matters. It is that the decking underneath becomes completely invisible.
Roof decking is the foundation of the entire system. If boards are soft, water damaged, or gapped beyond what code allows, nothing installed above them will perform properly. A layover guarantees that nobody finds out until the next roof.
In Oklahoma City the rules settle it. The city allows a single layer of shingles, so a replacement there means a full tear off, and since August 1, 2025 a re-roof on a house or duplex needs a city permit, with photos of the decked roof sent to the city before the inspection. Norman also allows one layer of asphalt shingles only.
What should happen instead: a complete tear off, followed by a proper inspection of the exposed deck. Where problems are found, they get documented and addressed rather than covered.
2. Using sealant where flashing belongs
Every place the roof meets something else is a potential leak: chimneys, wall junctions, valleys, and every pipe or vent that passes through the plane. These transitions are supposed to be handled with shaped, layered metal that directs water back out onto the roof surface.
Sealant is quicker. It also has a service life measured in a few years, after which it cracks and the leak arrives. When we investigate a roof that started leaking three years after replacement, the cause is very often a bead of caulk where a piece of flashing should have been.
What should happen instead: flashing in metal, detailed by hand at every transition. Sealant is a supplement to that work, never a replacement for it.
3. Ignoring ventilation
A roof needs to breathe. Without adequate intake at the eaves and exhaust at the ridge, the attic space beneath becomes an oven, and the decking cooks from below while the covering above degrades faster than it should.
Oklahoma summers make this considerably worse than it is in a milder climate. A roof that would have been marginal elsewhere is actively self destructive here.
What should happen instead: ventilation treated as part of the roof system and specified with it, not as an accessory somebody adds if there is budget left.
4. Not replacing the pipe boots
The rubber collar sealing around a plumbing vent has a shorter service life than the shingles around it. It sits in full sun, flexes with every temperature swing, and eventually splits.
Reusing existing boots on a new roof is a small saving and an entirely predictable future leak. It is also one of the most common causes of an interior water stain on a roof that is otherwise in perfect condition.
What should happen instead: new boots as part of the replacement, every time.
5. Nailing incorrectly
Fastener placement, quantity and depth all matter. Nails driven too high miss the layer they are meant to secure. Nails driven too deep cut through the shingle. Too few nails and the roof cannot handle the wind loads this state produces.
None of this is visible once the next course is laid, which is precisely why it gets rushed. It shows up during the first serious wind event.
What should happen instead: correct fastening to the manufacturer specification, and a foreman on site whose job includes checking it before it is covered.
6. Choosing a product nobody will stand behind
Some shingles are cheap because they are efficient. Some are cheap because there is a problem with them.
Our position is that we will not install a shingle we are not prepared to warranty ourselves. When a product we were installing was recalled, we stopped using it and went back to one we trusted.
What should happen instead: ask whoever is quoting whether they will warranty the specific product they are proposing, and what happens if it fails.
7. Treating the cleanup as optional
This one does not cause the roof to fail, but it is the part you live with. Roofing produces an extraordinary quantity of nails, and they end up in the grass, the driveway and the flowerbeds.
The related failure is not protecting landscaping before the tear off starts. A crew that starts dropping material without covering the flower beds first has created a problem that no amount of good roofing fixes.
What should happen instead: landscaping covered and protected before anything comes off the roof, and magnetic sweeps across the ground before the crew leaves.
The common thread
Every one of these is a time saving. None of them is visible when the job is finished, and all of them are the customer's problem rather than the roofer's. That is why the useful question to ask a contractor is not what shingle they are using. It is what happens underneath it, and who is on site making sure it happens.
If you want a second opinion on a roof, our assessment is free and you get the findings in writing whether or not there is anything to do about it.
